Hops (Humulus lupulus L.) is a plant that has been used for medicinal purposes for centuries and is currently used in the brewing industry. Hops contains both alpha acids (humulones) and beta acids (lupulones). Alpha acids/humulones have the general structure:

The three primary types of alpha acids are humulone (R═CH2CH(CH3)2), cohumulone (R═CH(CH3)2), and adhumulone (R═CH(CH3)CH2CH3). There are also two less common alpha acids in hops, prehumulone and posthumulone. Alpha acids can be converted to cis or trans iso-alpha acids/isohumulones by heat-induced isomerization of alpha acids, and these iso-alpha acids can in turn converted to cis or trans reduced iso-alpha acids by hydrogenation. The three primary types of reduced iso-alpha acids are dihydro- (also known as rho-), tetrahydro-, and hexahydro-iso-alpha acids (RIAA, THIAA, and HIAA, respectively).
Several compounds derived from hops have been found to possess anti-inflammatory activity (Hall 2008; Desai 2009; Tripp 2009; Konda 2010). THIAA extracts have been shown to inhibit inflammation (Desai 2009), reduce symptoms of arthritis in a mouse model of collagen-induced arthritis (Konda 2010), and improve glucose homeostasis in a high fat diet-induced metabolic endotoxemia model (Everard 2012). In each of these cases, the THIAA compounds shared a substituted 1,3-cyclopentadione motif.
The first attempts to identify the stereochemical configuration of the alpha acids and their derivatives were incorrect, starting with the alpha acids (which naturally have (−) optical rotation) and continuing through to the isomerized alpha acids. The alpha acids were originally given the 6R configuration, but are now known to be 6S. The correct stereochemical configuration was identified in U.S. Patent Publication No. 2012/0108671, which disclosed the stereochemical configuration of the THIAA cis 3,4-dihydroxy-2-(3-methylbutanoyl)-5-(3-methylbutyl)-4-(4-methylpentanoyl)cyclopent-2-en-1-one (“KDT500,” also known as cis tetrahydro isohumulone) based on X-ray crystallography data. There are two enantiomers of KDT500: (+)-(4S,5R)-3,4-dihydroxy-2-(3-methylbutanoyl)-5-(3-methylbutyl)-4-(4-methylpentanoyl)cyclopent-2-en-1-one (“(+)-KDT500”) and (−)-(4R,5S)-3,4-dihydroxy-2-(3-methylbutanoyl)-5-(3-methylbutyl)-4-(4-methylpentanoyl)cyclopent-2-en-1-one (“(−)-KDT500”). The structures of (+)-KDT500 and (−)-KDT500 are set forth in Formulas II and III, respectively.
U.S. Patent Publication No. 2012/0108671 describes the purification and characterization of KDT500 and its potassium salt KDT501. An enriched THIAA extract containing predominantly the cis diastereomers was obtained during hops processing and purified using countercurrent chromatography (CCC), and the isolated (+)-KDT500 was converted to (+)-KDT501 by reacting with 1 equivalent of potassium salt (e.g., KOH).

(+)-KDT501 was found to exhibit both anti-inflammatory and anti-diabetic effects.